U.S. patent application number 16/767373 was filed with the patent office on 2020-12-10 for method and device for checking the plausibility of a transverse movement.
The applicant listed for this patent is Robert Bosch GmbH. Invention is credited to Hermann Buddendick, Markus Schlosser.
Application Number | 20200386881 16/767373 |
Document ID | / |
Family ID | 1000005062222 |
Filed Date | 2020-12-10 |
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United States Patent
Application |
20200386881 |
Kind Code |
A1 |
Buddendick; Hermann ; et
al. |
December 10, 2020 |
METHOD AND DEVICE FOR CHECKING THE PLAUSIBILITY OF A TRANSVERSE
MOVEMENT
Abstract
A method for checking the plausibility of an initially known
transverse movement of an object. The method includes: emission of
a radar signal having constant signal frequency, and reception by a
radar device of reflections of the radar signal having constant
signal frequency; and checking the plausibility of the transverse
movement of the object by analyzing frequency ranges corresponding
to the transverse movement in a spectrum of the reflected radar
signal having constant signal frequency.
Inventors: |
Buddendick; Hermann;
(Sindelfingen, DE) ; Schlosser; Markus; (Jockgrim,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Robert Bosch GmbH |
Stuttgart |
|
DE |
|
|
Family ID: |
1000005062222 |
Appl. No.: |
16/767373 |
Filed: |
November 22, 2018 |
PCT Filed: |
November 22, 2018 |
PCT NO: |
PCT/EP2018/082298 |
371 Date: |
May 27, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 13/589 20130101;
G01S 13/583 20130101; G01S 13/931 20130101; G01S 2013/9318
20200101; G01S 2013/93271 20200101; G01S 2013/93185 20200101 |
International
Class: |
G01S 13/58 20060101
G01S013/58; G01S 13/931 20060101 G01S013/931 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2018 |
DE |
10 2018 200 755.1 |
Claims
1-10. (canceled)
11. A method for checking the plausibility of an initially known
transverse movement of an object, comprising the following steps:
emitting a radar signal having constant signal frequency, and
receiving by a radar device reflections of the radar signal having
constant signal frequency; and checking the plausibility of the
transverse movement of the object by analyzing frequency ranges
that correspond to the initially known transverse movement in a
spectrum of the reflected radar signal having constant signal
frequency.
12. The method as recited in claim 11, further comprising the
following step: calculating a relative speed and/or an azimuth
angle of the object based on the spectrum of the reflected radar
signal, wherein the checking of the plausibility of the transverse
movement of the object includes comparing the relative speed
calculated on based on the radar signal with the transverse
movement, and/or comparing the azimuth angle with the transverse
movement.
13. The method as recited in claim 12, further comprising the
following step: correcting the initially known transverse movement
of the object using the relative speed calculated based on the
radar signal and/or using the azimuth angle calculated based on the
radar signal.
14. The method as recited in claim 11, wherein the transverse
movement includes a transverse speed of the object.
15. The method as recited in claim 11, wherein the radar device is
situated on a vehicle, and the transverse movement includes a
lateral distance of the object from a lane of the vehicle.
16. The method as recited in claim 11, wherein the initially known
transverse movement is calculated based on FMCW radar data.
17. A device for checking the plausibility of an initially known
transverse movement of an object, comprising: a radar device
configured to emit a radar signal having constant signal frequency
and to receive reflections of the radar signal having constant
signal frequency; and a computing device configured to check the
plausibility of the transverse movement of the object by analyzing
frequency ranges corresponding to the transverse movement in a
spectrum of the reflected radar signal having constant signal
frequency.
18. The device as recited in claim 17, wherein the radar device is
configured to emit an FMCW-modulated radar signal and to calculate
the transverse movement based on received reflections of the
FMCW-modulated radar signal.
19. The device as recited in claim 18, wherein the radar device is
configured to emit temporally offset radar signals having constant
signal frequency and FMCW-modulated radar signals.
20. The device as recited in claim 17, further comprising: a
control device configured to control a driving function of a
vehicle based on the transverse movement, checked for plausibility,
of the object.
Description
FIELD
[0001] The present invention relates to a method for checking the
plausibility of an initially known transverse movement of an
object, and to a corresponding device. The present invention
relates in particular to driver assistance systems having such a
device.
BACKGROUND INFORMATION
[0002] Modern driver assistance systems have radar sensors for
monitoring the environment surrounding the vehicle. In contrast to
video cameras, radar sensors can directly measure the relative
speeds of an object, making use of the Doppler effect. An example
of a method for object detection is described in German Patent
Application No. DE 1994 9409 .mu.l.
[0003] So-called FMCW (frequency modulated continuous wave) methods
are in particularly wide use. In these methods, a radar signal
having a periodically modulated frequency is emitted, and the radar
signal reflected by an object is then received and evaluated. In
addition to the relative speed, the FMCW method makes it possible
to determine the distance to the object on the basis of the size of
the frequency difference between the emitted radar signal and the
received radar signal.
[0004] The measurement of object angles, i.e., azimuth angles of
the object relative to the main direction of transmission of the
radar device, is realized less accurately by radar sensors than by
video cameras. The accuracy is a function in particular of the
aperture of the radar sensor, and in particular of the width of the
array of the receive antenna. In addition, FMCW methods have
greater inaccuracy than CW methods, because the range analyzed in
the Doppler spectrum is more strongly interfered with by other
objects. In particular, the recognition of transverse movements,
i.e., movements of the object perpendicular to the direction of
movement of the radar device, or of the vehicle, are therefore
frequently difficult to correctly evaluate.
SUMMARY
[0005] The present invention provides a method for checking the
plausibility of an initially known transverse movement of an
object, and a device for checking the plausibility of an initially
known transverse movement of an object.
[0006] According to a first aspect, the present invention provides
a method for checking the plausibility of an initially known
transverse movement of an object. In accordance with an example
embodiment of the present invention, for this purpose, a radar
signal is emitted having a constant signal frequency, and
reflections of the radar signal having constant signal frequency
are received by a radar device. The transverse movement of the
object is checked for plausibility by analyzing frequency ranges in
a spectrum of the reflected radar signal having constant signal
frequency, these frequency ranges corresponding to the transverse
movement of the object.
[0007] According to a second aspect, the present invention provides
a device for checking the plausibility of an initially known
transverse movement of an object. In accordance with an example
embodiment of the present invention, the device includes a radar
device that emits a radar signal having constant signal frequency
and receives reflections of the radar signal having constant signal
frequency. A computing device is designed to check the plausibility
of the transverse movement of the object by analyzing frequency
ranges corresponding to the transverse movement in a spectrum of
the reflected radar signal having constant signal frequency.
[0008] Preferred specific embodiments of the present invention are
described herein.
[0009] The emitted radar signal is a transmission sequence having
constant signal frequency, preferably characterized by a duration
that significantly exceeds the duration of individual ramps of
FMCW-modulated radar signals. Therefore, on the basis of the radar
signal having constant signal frequency significantly higher speed
resolutions can be achieved than would be possible with the use of
FMCW-modulated radar signals. For example, the radar signal having
constant signal frequency can have a duration of 20 ms,
corresponding to a resolution in the range of approximately 0.1
m/s.
[0010] In addition to the higher speed resolution, the angular
resolution is in general also more accurate. In this way, an
initially known transverse movement of the object detected in some
other way can be checked for plausibility, one which was determined
for example on the basis of sensor data such as video data or,
particularly preferably, on the basis of FMCW-modulated radar
signals. In particular, critical transverse movements that
represent a risk of collision can be checked for plausibility.
[0011] In the sense of the present invention, "check for
plausibility" can be understood as meaning that the existence of
the detected object is verified or falsified. In particular, a
probability value can be calculated for the existence of the
object. In addition, this can be understood as meaning that the
precise movement of the object is checked. For this purpose, in
particular a criticality of the object movement can be calculated,
which can quantify for example a probability of a collision.
[0012] According to a preferred development of the example method
according to the present invention, the transverse movement of the
object is checked for plausibility if a Doppler shift that
corresponds to the object is detected in the frequency range.
[0013] According to a preferred development of the example method
according to the present invention, a relative speed and/or an
azimuth angle of the object are calculated on the basis of the
spectrum of the reflected radar signal having constant signal
frequency. The checking for plausibility of the transverse movement
of the object includes a comparison of the relative speed
calculated on the basis of the radar signal, and/or of the azimuth
angle calculated on the basis of the radar signal, with the
calculated transverse movement. In addition, the transverse
movement can be checked for plausibility if a Doppler shift in the
frequency spectrum of the radar signal having constant signal
frequency can be detected that corresponds to a relative speed,
determined using the FMCW-modulated radar signals, between the
object and the radar device, or a vehicle that has the radar
device. In this way, according to this specific embodiment a
transverse movement can include in particular a transverse speed
and/or a relative speed of the object. A transversely moving object
typically always has a radial component in the direction of the
radar device that causes a Doppler shift. By determining this
Doppler shift, the device can confirm the existence of a
transversely moving object.
[0014] According to a preferred development of the example method
according to the present invention, the initially known transverse
movement of the object can be corrected using the transverse
movement calculated on the basis of the radar signal. Because the
transverse speed calculated on the basis of the radar signal having
constant signal frequency is typically significantly more accurate,
in this way the initially known transverse movement can be checked
for plausibility, and typically can also be determined more
precisely. In particular, a relative speed between the device, or
the vehicle, and the object can be calculated and corrected on the
basis of Doppler shifts.
[0015] According to a development of the example method, the
transverse movement of the object includes a transverse speed of
the object. In addition, the transverse movement can include a
lateral distance of the object from a lane of a vehicle that has
the radar device. The transverse speed and the lateral distance are
of particular interest, because they principally influence the
probability of a collision. These variables can be determined on
the basis of the Doppler spectrum, and further information can also
be taken into account. In particular, the radial distance of the
initially known transverse movement can be taken into account.
[0016] According to a preferred development of the example method
in accordance with the present invention, on the basis of the
spectrum of the reflected radar signal a lateral distance of the
object from a lane of the vehicle or from a trajectory of the
vehicle is calculated. The checking of the plausibility of the
transverse movement of the object includes a comparison of the
lateral distance, calculated on the basis of the radar signal, with
the calculated transverse movement of the object. In particular,
the transverse movement can be calculated on the basis of sensor
data, and in addition on the basis of the sensor data a lateral
distance can be estimated that is compared with the lateral
distance calculated on the basis of the radar data. A lateral
distance is to be understood as the distance to the object measured
perpendicular to the lane, or to the trajectory, of the vehicle.
The closer an object is situated to the lane, the higher the
probability of a collision. Through precise knowledge of the
lateral distance, such situations can be recognized in good time,
and in this way safety can be increased. In this way, critical and
uncritical situations can be reliably distinguished in order to
avoid unjustified emergency braking. Thus, according to this
specific embodiment the transverse movement includes in particular
a lateral distance.
[0017] According to a preferred development of the example method
according to the present invention, an object angle of the object
is determined on the basis of the spectrum of the reflected radar
signal. The lateral distance is calculated using the calculated
object angle of the object and the distance of the object
calculated on the basis of the sensor data. Because, as stated
above, the angular resolution of radar signals having constant
signal frequency is very high, the object angle, and thus the
lateral distance, can be calculated with a high degree of
precision.
[0018] According to a preferred development of the example method
according to the present invention, the sensor data for calculating
the transverse movement include FMCW radar data. According to
further specific embodiments of the present invention, the sensor
data can be generated by video cameras, infrared sensors, or lidar
sensors, or by any combination of these sensors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows a schematic block diagram of a device for
checking the plausibility of an initially known transverse movement
of an object according to a first specific embodiment of the
present invention.
[0020] FIG. 2 shows a schematic block diagram of a device for
checking the plausibility of an initially known transverse movement
of an object according to a second specific embodiment of the
present invention.
[0021] FIG. 3 shows a schematic top view of an object, as well as a
vehicle having a device according to a specific embodiment of the
present invention.
[0022] FIG. 4 shows a flow diagram of a method for checking the
plausibility of a transverse movement according to a first specific
embodiment of the present invention.
[0023] FIG. 5 shows a flow diagram of a method for checking the
plausibility of a transverse movement according to a second
specific embodiment of the present invention.
[0024] In all the Figures, identical or functionally identical
elements and devices are provided with the same reference
characters.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0025] FIG. 1 shows a block diagram of a device 1a for checking the
plausibility of an initially known transverse movement, for example
calculated using sensor data, of an object in the environment of a
vehicle, according to a first specific embodiment of the present
invention. The object can be for example a bicyclist, a pedestrian,
or another vehicle. Device 1a can be designed as a driver
assistance system, or can be part of a driver assistance system of
the vehicle. Device 1a includes an interface 4 that is designed to
receive sensor data from sensors of the vehicle in wireless fashion
or via a wired connection.
[0026] The sensor data include information concerning a transverse
movement of an object in the environment of the vehicle, including
in particular a transverse speed of the object and, optionally, in
addition a lateral distance of the object from the lane of the
vehicle. The data received via interface 4 are sent to a computing
device 3 of device 1a.
[0027] Device 1a further has a radar device 2 that is situated on
the vehicle and that emits and receives radar signals. For this
purpose, radar device 2 emits radar signals or signal sequences
having a constant signal frequency. The duration of the individual
signal sequences is preferably at least 10 ms, particularly
preferably at least 20 ms. Radar device 2 receives reflections of
the radar signal having constant signal frequency and generates
radar data that are also sent to computing device 3.
[0028] Computing device 3 includes at least one microprocessor that
is designed to evaluate the data received from interface 4 and
radar device 2. From the radar data, computing device 3 generates a
frequency spectrum of the reflected radar signal having constant
signal frequency. Computing device 3 further checks whether the
relative speed of the object, calculated on the basis of the sensor
data, can also be recognized in the frequency spectrum of the
reflected radar signal having constant signal frequency. Computing
device 3 thus checks whether, in the corresponding frequency
ranges, an amplitude exceeds a specified threshold value. If this
is the case, then computing device 3 recognizes that there is a
corresponding Doppler shift in the radar signal. The calculated
transverse speed can be checked for plausibility in this way. In
particular, the existence of an actual physical transverse movement
can be distinguished from migration of a reflection point.
Optionally, as a function of the magnitude of the amplitude,
computing device 3 can in addition indicate a plausibility variable
relating to the extent to which the transverse speed can be checked
for plausibility or not. The greater the amplitude, the higher the
probability that an object having the radial speed or transverse
speed, calculated on the basis of the sensor data, is actually
present in the environment of the vehicle, because an additional
check based on the radar signal having constant signal frequency is
successful. The plausibility variable is correspondingly increased.
Conversely, the plausibility variable can be decreased if no peaks
are recognized in the corresponding frequency range.
[0029] Computing device 3 can also be designed to correct the
transverse speed calculated on the basis of the sensor data. If,
for example, there is a peak in the frequency spectrum of the
reflected radar signal having constant signal frequency at a value
close to the radial speed or transverse speed calculated on the
basis of the sensor data, and the peak has an amplitude that
exceeds a specified threshold value, then computing device 3 can
correct the estimated value of the transverse speed in this
direction.
[0030] Optionally, computing device 3 can in addition be designed
to extract a lateral distance of the object from the lane from the
radar data. For this purpose, radar device 2 can for example have a
multiplicity of radar sensors, or one radar sensor having a
multiplicity of transmit and receive antennas, so that a
corresponding object angle of the object can be determined via
phase differences of the received radar signal having a constant
signal frequency. If the radar sensors have the same orientation,
then the object angle is determined relative to the common main
axis of radiation. Computing device 3 then compares the object
angle extracted from the radar data with the object angle measured
on the basis of the sensor data. For this purpose, computing device
3 is designed to check the plausibility of the object angle
measured on the basis of the sensor data, i.e., to check whether
the object angle measured on the basis of the sensor data agrees
with the object angle extracted on the basis of the radar data. A
corresponding plausibility variable can be adapted as a function of
the result of the comparison.
[0031] According to some specific embodiments of the present
invention, the angular analysis can be carried out only if the
relative speed is not too low, causing the corresponding Doppler
frequencies to be very small and difficult to detect. In this case
in particular, a superposition with stationary objects may occur.
An angular range to be investigated can be further limited on the
basis of the angular range calculated using the sensor data. The
position and size of the frequency interval to be analyzed is more
generally adapted to the speed of movement and direction of
movement of the ascertained transverse movement. The greater the
absolute object speed, and the closer the direction of movement is
to an exactly perpendicular direction of movement, the greater the
frequency range to be analyzed is. Occlusion effects can preferably
also be taken into account in the calculation of the
plausibilization variable. The stronger the disturbance by other
objects of the frequency interval to be analyzed around the
predicted Doppler frequency, the smaller is the reduction in a
probability value of the existence of a transversely crossing
object on the basis of the radar signal having constant signal
frequency, if no matching Doppler frequency can be found.
Preferably, for this purpose the ratio is calculated between the
expected receive power, which is calculated from the estimated
radar cross-section and the distance to the object, and the
measured interference power level.
[0032] Device 1a further includes a control device 5 that controls
a driving function of the vehicle on the basis of the transverse
movement, checked for plausibility, of the object. If the
transverse movement of the object evaluated on the basis of the
sensor data is confirmed, i.e., is also found again in the
frequency spectrum of the reflected radar signal having constant
signal frequency, control device 5 can introduce countermeasures if
warranted in order to avoid a collision. On the basis of the
transverse movement, for example a collision region and a collision
time can be ascertained. Control device 5 can correspondingly steer
or brake the vehicle. In particular, control device 5 can carry out
an emergency braking. However, control device 5 can also be
designed to output a warning signal to the driver of the
vehicle.
[0033] Such a controlling of the vehicle need not necessarily be
prevented if the transverse movement calculated on the basis of the
sensor data cannot be checked for plausibility. If the object
tracking based on the sensor data already has a very high
confidence level, then, despite an absence of confirmation by the
radar signal having constant signal frequency, an emergency braking
can nonetheless be carried out. Such situations can occur in
particular when the object is occluded by other objects.
[0034] FIG. 2 illustrates a block diagram of a device 1b according
to a second specific embodiment of the present invention. This
device differs from device 1a illustrated in FIG. 1 in that the
sensor data are produced by radar device 2 itself. According to
this specific embodiment, radar device 2 produces temporally offset
FMCW-modulated radar signals, the reflected FMCW-modulated radar
signals being received and corresponding sensor data being
outputted. Computing device 3 is designed to calculate a transverse
movement of the object in the environment of the vehicle on the
basis of the sensor data, i.e., in particular to determine a
transverse speed and, preferably, in addition a lateral distance to
the object.
[0035] Computing device 3 is further designed to check the
plausibility of the variables of the transverse movement of the
object, calculated on the basis of the sensor data. For this
purpose, radar device 2 emits radar signals having constant signal
frequency, temporally offset to the FMCW-modulated radar signals,
and generates radar data on the basis of the received reflected
radar signals having constant signal frequency. As described above,
computing device 3 checks whether a corresponding relative speed is
to be found in the frequency spectrum. If this is the case, then
computing device 3 can in addition extract and compare the lateral
distance.
[0036] In other respects, the design of device 1a corresponds to
the first specific embodiment, and is therefore not described
again.
[0037] FIG. 3 shows an example of a scenario. Vehicle 6 has one of
the above-described devices 1a, 1b. In particular, a radar device 2
is situated on the front of vehicle 6. Vehicle 6 moves along a home
trajectory 9 with a home speed v_ego. On the basis of sensor data,
an object 7 is recognized at an object angle .PHI. that is measured
relative to the direction of travel, or relative to the main
direction of radiation of radar device 2. Object 7 moves with an
object speed v_obj along object trajectory 8, towards a point of
intersection 11 with home trajectory 9. The transverse speed of
object 7 corresponds to the speed component perpendicular to the
travel direction or lane. Object 7 has a radial speed v_rad in the
direction of vehicle 6 that corresponds to the projection of object
speed v_obj onto a connecting line 10 between radar device 2 and
object 7. The relative speed of object 7 is in addition a function
of the speed of vehicle 6. Object 7 has a lateral distance d from a
roadway boundary 12, and has a trajectory distance D from the home
trajectory of vehicle 6. As described above, device 1a, 1b of
vehicle 6 is designed to check the plausibility of the transverse
movement calculated on the basis of the sensor data. For this
purpose, device 1a, 1b checks on the one hand whether the existence
of object 7 can be confirmed on the basis of the radar signals
having constant signal frequency, and whether, if warranted, the
transverse movement can be corrected. In particular, the transverse
movement and/or the lateral distance of object 7 can be checked and
corrected.
[0038] FIG. 4 shows a flow diagram of a method according to a
specific embodiment of the present invention. For this purpose, in
a method step S11 sensor data are produced and a transverse
movement of an object 7 in the environment of a vehicle 6 is
calculated. The sensor data are preferably generated by
FMCW-modulated radar signals.
[0039] In a method step S12, on the basis of the calculated
transverse movement it is checked whether a collision between
vehicle 6 and object 7 is probable. If the calculated probability
exceeds a specified threshold value, it is recognized that a
critical transverse movement is present. In a method step S13, an
analysis of the Doppler spectrum of an emitted and received radar
signal having constant signal frequency is carried out. Otherwise,
the next measurement cycle is analyzed (S11).
[0040] The analysis of the Doppler spectrum includes a checking of
the plausibility of the transverse movement. Building on this, in a
step S14 a probability of the existence of the object is
ascertained, and in a method step S15 a countermeasure is
introduced, for example an outputting of an acoustic, visual, or
optical warning signal, a warning via a brief braking, an evasive
maneuver, or an emergency braking.
[0041] According to a specific embodiment of the present invention,
an emergency braking can also be carried out as soon as a
corresponding Doppler frequency is found.
[0042] FIG. 5 shows a flow diagram of a method for checking the
plausibility of a transverse movement of an object 7, calculated
using sensor data, in the environment of a vehicle 6, according to
a second specific embodiment of the present invention.
[0043] In a method step S21, the transverse movement of the object
is ascertained on the basis of the sensor data in the manner
described above.
[0044] In method step S22, on the basis of the sensor data it is
checked whether the transverse movement is a critical transverse
movement. The threshold as to whether a critical transverse
movement is present can here preferably be chosen to be smaller
than in step S12 of the method illustrated in FIG. 4.
[0045] Accordingly, transverse movements that are only slightly
critical can also be investigated.
[0046] In a method step S23, such transverse movements are checked
for plausibility as described above through analysis of the Doppler
spectrum of a radar signal having constant signal frequency.
[0047] In method step S24 it is checked whether the radar signal
having constant signal frequency confirms the transverse movement.
If this is the case, then in a method step S25 the object movement
is corrected if warranted. Otherwise, in a method step S26 the
probability of the existence of the object, or the probability of a
collision, is reduced. In a method step S27, it is checked whether
the probability of existence is high enough. If this is not the
case, the method is carried out again. Otherwise, and following
method step S25, in a method step S28 it is checked whether the
movement is critical enough, i.e. whether a collision is probable.
If this is not the case, the method is repeated; otherwise one of
the countermeasures described above is introduced (S29).
* * * * *